In an AM and an FM receivers, a local oscillator circuit generates a signal having a certain frequency difference from a received signal and converts the received signal into a specified intermediate frequency signal by mixing the received signal with the local oscillation signal.
In making an AM or FM receiver circuit by an integrated circuit (“IC” hereinafter), a local oscillator circuit has been separately mounted onto a printed circuit board having an IC for the receiver mounted thereon, because capacitances and inductance values for gaining a signal having a required oscillation frequency are too large for forming the capacitors and inductances within the IC.
This has required externally mounted components for a receiver or transmitter IC, causing a problem of higher component and assembly costs. Furthermore, there has also been a problem of an increased size of the printed circuit board in need of space for mounting capacitors and coils thereon.